dpaa2-eth: check fsl_mc_get_endpoint for IS_ERR_OR_NULL()

The fsl_mc_get_endpoint() function can return an error or directly a
NULL pointer in case the peer device is not under the root DPRC
container. Treat this case also, otherwise it would lead to a NULL
pointer when trying to access the peer fsl_mc_device.

Fixes: 71947923 ("dpaa2-eth: add MAC/PHY support through phylink")
Signed-off-by: NIoana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/freescale/dpaa2/dpaa2-eth.c

@@ -3632,7 +3632,7 @@ static int dpaa2_eth_connect_mac(struct dpaa2_eth_priv *priv)
 
 	dpni_dev = to_fsl_mc_device(priv->net_dev->dev.parent);
 	dpmac_dev = fsl_mc_get_endpoint(dpni_dev);
-	if (IS_ERR(dpmac_dev) || dpmac_dev->dev.type != &fsl_mc_bus_dpmac_type)
+	if (IS_ERR_OR_NULL(dpmac_dev) || dpmac_dev->dev.type != &fsl_mc_bus_dpmac_type)
 		return 0;
 
 	if (dpaa2_mac_is_type_fixed(dpmac_dev, priv->mc_io))